This invention relates generally to expansion joints of the type used in an expansion joint space or gap to protect against the intrusion of dirt, water and other debris, as for example might be encountered by expansion joints employed in roadway construction. More specifically, the present invention relates to a molded elastomeric expansion seal construction that may be employed in a joint assembly having elongated elastomeric edge members or marginal bodies installed on both sides of the gap as defined by a pair of structural members such as concrete slabs wherein a flexible elastomeric sealing means spans the gap and is connected between said marginal bodies.
One problem encountered with many available expansion joint assemblies is that the longitudinal edge portions of the seal associated therewith become dislodged from the slab members or marginal bodies associated therewith over part or all of the longitudinal lengths of the joint with the result that the seal no longer remains watertight and thus, ceases to perform one of the principal functions for which it was provided.
There have been various proposals for the design of elastomeric seals or "strip seals" as they have become known and the longitudinal edge constructions therefor which have had the objective of minimizing the possibility of failure of the joint by dislodging of the seal from the slab members. In regard to expansion seals having mounting beads along the longitudinal edges thereof for mounting in a corresponding cavity of the slab members, a number of specific problems have been encountered. It has been found very difficult in the prior art to form metal edge members, adapted for assembly in the slab members, having cavities therein of predetermined cross-sections which include any degree of high tolerance along the entire extruded length thereof. For example, in extruding a metal edge member with a cavity therein on the order of 16 feet in longitudinal length as might be utilized in a road joint, it has been found that the extrusion process fails to maintain uniformity in the cross-sectional dimensions of the cavity along the entire longitudinal length thereof. On the other hand, it has been found possible in the prior art to maintain a relatively high degree of tolerance with respect to the outer surface cross-sectional dimensions of an extruded mounting or retaining bead of an expansion seal. Necessarily, the resultant differences in uniformity between the aforesaid seal beads and associated cavities result in the possibility of the beads being more easily dislodged from such metal edge members. Applicant's U.S. Pat. No. 3,994,609, issued Nov. 30, 1976 to the assignee of the present invention, discloses a seal bead and related edge member cavity construction overcoming these problems.
However, when considering the use of a molded elastomeric edge member or marginal body for retaining the longitudinal edge of a strip seal in mounted position with a slab member in an effective manner, a number of problems have been encountered in regard to providing a watertight seal wherein the components of the joint will not dislodge from one another. Necessarily, an elastomeric edge member or marginal body unlike a metal edge member is subject to deformation which in turn can affect its effective engagement with and retention of a sealing strip. Furthermore, it is necessary that the bottom surface of such an elastomeric edge member firmly engage the underlying slab member so that water may not pass therebetween. Furthermore, it is desirable to insure that the longitudinal edges of the marginal body do not curl up or lift up vertically with respect to the slab members when assembled therewith whereby the watertightness of the construction could be jeopardized as well as its resistance to wear from traffic passing thereover.